CN102116797A - High accuracy numerical frequency measurement method based on FPGA - Google Patents

High accuracy numerical frequency measurement method based on FPGA Download PDF

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CN102116797A
CN102116797A CN2010106108863A CN201010610886A CN102116797A CN 102116797 A CN102116797 A CN 102116797A CN 2010106108863 A CN2010106108863 A CN 2010106108863A CN 201010610886 A CN201010610886 A CN 201010610886A CN 102116797 A CN102116797 A CN 102116797A
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impulsive synchronization
time clock
signal
frequency
standard time
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马城城
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Tianjin 764 Communication and Navigation Technology Corp
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Abstract

The invention relates to a high accuracy numerical frequency measurement method based on a FPGA (Field Programmable Gate Array), which is characterized in that: by setting up a pulse synchronous detection circuit, a pulse synchronous moment detected by the pulse synchronous detection circuit is taken as an opening/closing signal so that the actual opening and closing of a gate occur at the moment to which both a standard clock and a measured signal are close enough, thus the error is minimized; a measurement circuit comprises the FPGA, the pulse synchronous detection circuit and a display circuit; the problem that the measurement accuracy of restricted frequency is raised to +/- 1 word counting error, thereby improving the accuracy and the performance of frequency measurement remarkably.

Description

Pin-point accuracy numerical frequency measuring method based on FPGA
Technical field
The present invention relates to the communication measurement technical field, particularly a kind of pin-point accuracy numerical frequency measuring method based on FPGA.
Background technology
Frequency is as a kind of the most basic to physical quantity, and its problems of measurement is equal to the time to measuring, and is not only extremely important in engineering is used, and is in core status in the pin-point accuracy real-time system.In the frequency measurement process of reality ± existence of 1 a word count error major reason further improving of limit frequency accuracy of measurement often.Because the importance of frequency measurement technology makes its measuring method that very big development arranged, method commonly used has very M/T method of M method, T method, but these three kinds of methods all exist ± 1 word count error problem.The M method is to measure the pulse number of measured signal in given time gate.When measured signal was low, error was bigger, unless gate time is very long, relatively was fit to measure high-frequency signal.The T method is to converse frequency again by the cycle of measuring measured signal, and its accuracy of measurement depends on the cycle and the accuracy of timekeeping of measured signal, relatively is fit to measure low frequency signal.The M/T method is comprehensive above-mentioned two kinds of methods, converses frequency again by the time of measuring several cycles of measured signal, has improved the accuracy of measurement result.These three kinds of methods respectively have superiority, but the accuracy that all can't further improve measurement result.
Summary of the invention
Purpose of the present invention is exactly for overcoming the deficiencies in the prior art, at in the MMLS system in order to realize the actual demand of the frequency measurement function that monitoring means need newly add, designed this frequency measuring method fully synchronously based on FPGA, utilize complete synchronism eliminates the limit frequency accuracy of measurement bring up to ± 1 word count error problem, thereby the accuracy of frequency measurement and performance are greatly improved.
The present invention realizes by such technical scheme: a kind of pin-point accuracy numerical frequency measuring method based on FPGA, and it is characterized in that: described method comprises following order step:
(1) make standard time clock, measured signal and signal strobe sequential be: signal strobe is not only synchronous with measured signal, and is also synchronous with standard time clock;
(2) provide with reference to behind the signal strobe, the synchronizing information by impulsive synchronization detecting device detection measured signal pulse edge and standard clock signal pulse edge then picks up counting when both are synchronous; Behind closing gate, detect the synchronizing information of measured signal pulse edge and standard time clock pulse edge equally by the impulsive synchronization detecting device, when both are synchronous, then stop timing;
(3) by building the impulsive synchronization testing circuit, utilize the impulsive synchronization testing circuit to detect the moment of impulsive synchronization as switching signal, make the switch of actual gate occur in the standard time clock and all enough approaching moment of measured signal, thereby reach minimizing of error;
A kind of pin-point accuracy numerical frequency metering circuit based on FPGA comprises by FPGA, impulsive synchronization testing circuit and display circuit; It is characterized in that described impulsive synchronization testing circuit is made of 74LS series Sheffer stroke gate integrated circuit (IC) chip, comprises Sheffer stroke gate U1～U8 in the Sheffer stroke gate integrated circuit (IC) chip; Described fpga chip inside comprises 2 counters, 2 registers, controller, sequential multiplier, divider, decoding scheme;
Given impulsive synchronization testing circuit and 2 counters respectively by measured frequency and standard time clock, when the impulsive synchronization testing circuit detects by measured frequency and standard time clock when synchronous, the impulsive synchronization testing circuit sends synchronizing signal, and 2 counters begin counting.
When detecting synchronizing signal once more, sends the impulsive synchronization testing circuit synchronizing signal again, counter stops counting, the counting of unison counter is deposited register, the sequential multiplier is obtained from register by the count value of measured frequency and standard time clock frequency and is carried out multiplying, and then give divider with the value of multiplier computing gained and the count value of standard time clock, the result of multiplier is a dividend, and the count value of standard time clock is a divisor, and the result of computing gained is exactly the frequency of measured signal.
The present invention uses the pin-point accuracy numerical frequency measuring method based on FPGA, by building the impulsive synchronization testing circuit, utilize the impulsive synchronization testing circuit to detect the moment of impulsive synchronization as switching signal, make the switch of actual gate occur in the standard time clock and all enough approaching moment of measured signal, thereby reach minimizing of error; Metering circuit comprises by FPGA, impulsive synchronization testing circuit and display circuit; Utilize complete synchronism eliminates limit frequency accuracy of measurement to bring up to ± 1 word count error problem, thereby the accuracy of frequency measurement and performance are greatly improved.
Description of drawings
Fig. 1, system principle diagram;
Fig. 2, full frequency measurement schematic diagram synchronously;
Fig. 3, impulsive synchronization testing circuit principle.
Embodiment
For a more clear understanding of the present invention, describe the present invention in conjunction with the accompanying drawings and embodiments in detail:
Based on the pin-point accuracy numerical frequency metering circuit of FPGA, comprise as shown in Figure 1 by FPGA, impulsive synchronization testing circuit and display circuit;
Complete as shown in Figure 2 frequency measurement principle synchronously: under full synchronous situation, signal strobe is not only synchronous with measured signal, also synchronous with standard time clock, after providing with reference to signal strobe, by the synchronizing information of an impulsive synchronization detecting device detection measured signal pulse edge and standard clock signal pulse edge, when they just pick up counting synchronously; Behind closing gate, the synchronizing information of same detection measured signal pulse edge and standard time clock pulse edge is when they then stop timing synchronously.
In fact the synchronous moment opens fully will to find both pulses for standard time clock and measured signal arbitrarily, closed shutter is unpractical, but can build the impulsive synchronization testing circuit, utilize this impulsive synchronization testing circuit to detect the moment of impulsive synchronization as switching signal, can be so that the switch of actual gate occur in the standard time clock and all enough approaching moment of measured signal, thus reach minimizing of error.If the pulse synchronization time difference is during starting gate
Figure 518039DEST_PATH_IMAGE001
, the pulse synchronization time difference is during closed shutter , impulsive synchronization detects maximum error and is
Figure 755303DEST_PATH_IMAGE003
, then have:
Figure 382724DEST_PATH_IMAGE004
,
Figure 267504DEST_PATH_IMAGE005
Disregard the standard time clock error, actual gate and standard time clock are synchronous, and be actual gate time
Figure 347586DEST_PATH_IMAGE006
, then the frequency measurement of measured signal is:
Figure 546486DEST_PATH_IMAGE007
…………………………（1）
In the formula:
Be the measured signal periodicity;
Figure 84095DEST_PATH_IMAGE009
Be the standard time clock frequency;
Figure 900741DEST_PATH_IMAGE010
Be the measured signal frequency measurement;
Figure 903332DEST_PATH_IMAGE011
Be the standard time clock periodicity;
Figure 236837DEST_PATH_IMAGE006
Be actual gate time;
Measured signal frequency true value can be:
Figure 463419DEST_PATH_IMAGE012
(2)
In the formula:
Figure 705045DEST_PATH_IMAGE013
Be measured signal frequency true value.
The relative error of measuring is: (3)
By formula (3) as can be known, measuring error is only relevant with the pulse-detecting circuit accuracy, control
Figure 499005DEST_PATH_IMAGE003
The standard time clock frequency is easier than improving.In full frequency measuring method synchronously, when
Figure 99751DEST_PATH_IMAGE003
=2.5ns,
Figure 376143DEST_PATH_IMAGE006
During=0.001s, can realize 1000 times/s, relative accuracy reaches
Figure 782853DEST_PATH_IMAGE015
Dynamic frequency is measured fast.
On the basis of above analysis, the design adopts FPGA to realize full synchronous digital frequency measurement, and as shown in Figure 1, the overwhelming majority of design is finished by FPGA, has only the impulsive synchronization testing circuit to be made of 74LS series Sheffer stroke gate and display circuit.
FPGA internal module circuit is made up of 2 counters, 2 registers, controller, multiplier, divider, decoding scheme etc.Principle of work is as follows: given impulsive synchronization testing circuit and 2 counters respectively by measured frequency and standard time clock, when the impulsive synchronization testing circuit detects by measured frequency and standard time clock when synchronous, the impulsive synchronization testing circuit sends synchronizing signal, and 2 counters begin counting; When detecting synchronizing signal once more, sends the impulsive synchronization testing circuit synchronizing signal again, counter stops counting, the counting of unison counter is deposited register, the sequential multiplier is obtained from register by the count value of measured frequency and standard time clock frequency and is carried out multiplying, and then give divider with the value of multiplier computing gained and the count value of standard time clock, the result of multiplier is a dividend, and the count value of standard time clock is a divisor, and the result of computing gained is exactly the frequency of measured signal.Wherein, whether detection signal and standard time clock be synchronous and produce the key component of actual control gate signal when impulsive synchronization detected, and its electric property directly has influence on the accuracy of frequency measurement.
Impulsive synchronization testing circuit principle as shown in Figure 3.Among the figure, ～
Figure 599948DEST_PATH_IMAGE017
Be 74LS series Sheffer stroke gate, sync detection circuit utilizes the time-delay of gate circuit to constitute.When measured signal and standard time clock all are in low level,
Figure 612903DEST_PATH_IMAGE016
, The output high level, ,
Figure 662877DEST_PATH_IMAGE020
The output high level, ,
Figure 600057DEST_PATH_IMAGE022
Output low level,
Figure 869365DEST_PATH_IMAGE023
The output high level, then
Figure 982814DEST_PATH_IMAGE024
Output low level.When
Figure 721094DEST_PATH_IMAGE013
With
Figure 945402DEST_PATH_IMAGE025
Rising edge when arriving simultaneously because the time delay of gate circuit,
Figure 334795DEST_PATH_IMAGE016
,
Figure 166616DEST_PATH_IMAGE018
Do not become low level at once, but will just become low level through a time-delay, so
Figure 641460DEST_PATH_IMAGE019
,
Figure 669459DEST_PATH_IMAGE020
Input end all be high level, then
Figure 661161DEST_PATH_IMAGE019
,
Figure 178730DEST_PATH_IMAGE020
Output low level,
Figure 626023DEST_PATH_IMAGE021
, The output high level,
Figure 556119DEST_PATH_IMAGE023
Output low level, then
Figure 995321DEST_PATH_IMAGE024
The output high level.And can see that and if only if With
Figure 548980DEST_PATH_IMAGE025
Rising edge when in time delay, arriving simultaneously
Figure 518204DEST_PATH_IMAGE024
Just export high level.The time-delay minimum of 74LS Sheffer stroke gate is 4ns, be 15ns to the maximum, so maximum error is 11ns.According to formula
Figure 377575DEST_PATH_IMAGE026
, when
Figure 819968DEST_PATH_IMAGE027
During=1s, its accuracy can reach
Figure 727881DEST_PATH_IMAGE028
If, reduce the synchronous detection error again, can improve accuracy of measurement again.
This method is to exchange accuracy for the sacrifice time to a certain extent, but the frequency measurement system is not high to the requirement of time in reality is measured, electronic system is more and more higher to the requirement of system clock accuracy on the contrary, so it has application space more widely.
According to the above description, can realize the solution of the present invention in conjunction with art technology.

Claims (2)

1. pin-point accuracy numerical frequency measuring method based on FPGA, it is characterized in that: described method comprises following order step:
(1) make standard time clock, measured signal and signal strobe sequential be: signal strobe is not only synchronous with measured signal, and is also synchronous with standard time clock;
(2) provide with reference to behind the signal strobe, the synchronizing information by impulsive synchronization detecting device detection measured signal pulse edge and standard clock signal pulse edge then picks up counting when both are synchronous; Behind closing gate, detect the synchronizing information of measured signal pulse edge and standard time clock pulse edge equally by the impulsive synchronization detecting device, when both are synchronous, then stop timing;
(3) by building the impulsive synchronization testing circuit, utilize the impulsive synchronization testing circuit to detect the moment of impulsive synchronization as switching signal, make the switch of actual gate occur in the standard time clock and all enough approaching moment of measured signal, thereby reach minimizing of error.
2. the pin-point accuracy numerical frequency metering circuit based on FPGA comprises by FPGA, impulsive synchronization testing circuit and display circuit; It is characterized in that described impulsive synchronization testing circuit is made of 74LS series Sheffer stroke gate integrated circuit (IC) chip, comprises Sheffer stroke gate U1～U8 in the Sheffer stroke gate integrated circuit (IC) chip; Described fpga chip inside comprises 2 counters, 2 registers, controller, sequential multiplier, divider, decoding scheme; Given impulsive synchronization testing circuit and 2 counters respectively by measured frequency and standard time clock, when the impulsive synchronization testing circuit detects by measured frequency and standard time clock when synchronous, the impulsive synchronization testing circuit sends synchronizing signal, and 2 counters begin counting; When detecting synchronizing signal once more, sends the impulsive synchronization testing circuit synchronizing signal again, counter stops counting, the counting of unison counter is deposited register, the sequential multiplier is obtained from register by the count value of measured frequency and standard time clock frequency and is carried out multiplying, and then give divider with the value of multiplier computing gained and the count value of standard time clock, the result of multiplier is a dividend, and the count value of standard time clock is a divisor, and the result of computing gained is exactly the frequency of measured signal.
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CN102495283A (en) * 2011-12-09 2012-06-13 中国人民解放军第二炮兵计量站 Self-adaptive equal-precision frequency measuring method
CN102497199A (en) * 2011-11-29 2012-06-13 中国西电电气股份有限公司 1/2-period frequency measuring system and method
CN102621384A (en) * 2012-04-09 2012-08-01 浙江中控技术股份有限公司 Frequency measuring method and frequency measuring system
EP2546663A1 (en) * 2011-07-15 2013-01-16 Askey Technology (Jiangsu) Ltd. Method and system for measuring frequency
EP2546662A1 (en) * 2011-07-15 2013-01-16 Askey Technology (Jiangsu) Ltd. Frequency counter
CN102928677A (en) * 2012-11-09 2013-02-13 湖南航天远望测控技术有限公司 Nano pulse signal acquiring method
CN103018556A (en) * 2011-09-21 2013-04-03 亚旭电子科技(江苏)有限公司 Frequency counter
CN103018745A (en) * 2011-09-21 2013-04-03 亚旭电子科技(江苏)有限公司 Distance measuring method and system
CN104931779A (en) * 2015-05-08 2015-09-23 中国电子科技集团公司第四十一研究所 Single-channel realized continuous frequency measure method
CN106302014A (en) * 2016-08-12 2017-01-04 电信科学技术第五研究所 The signal measurement method of wide-range high-precision
CN107247183A (en) * 2017-06-09 2017-10-13 中国电子科技集团公司第四十研究所 A kind of phase measuring system and method
CN108647173A (en) * 2018-08-01 2018-10-12 中国电子科技集团公司第三十四研究所 A kind of synchronous start pulse signal regenerating unit and its operation method
CN110954745A (en) * 2019-11-14 2020-04-03 中国航空工业集团公司西安航空计算技术研究所 High-precision frequency acquisition method and device based on FPGA
CN112698093A (en) * 2020-12-17 2021-04-23 南京爱浦克施电气有限公司 High-precision quick frequency measuring device

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CN102879641A (en) * 2011-07-15 2013-01-16 亚旭电子科技(江苏)有限公司 Frequency measurement method and system
EP2546663A1 (en) * 2011-07-15 2013-01-16 Askey Technology (Jiangsu) Ltd. Method and system for measuring frequency
EP2546662A1 (en) * 2011-07-15 2013-01-16 Askey Technology (Jiangsu) Ltd. Frequency counter
CN103018745A (en) * 2011-09-21 2013-04-03 亚旭电子科技(江苏)有限公司 Distance measuring method and system
CN103018556A (en) * 2011-09-21 2013-04-03 亚旭电子科技(江苏)有限公司 Frequency counter
CN102497199B (en) * 2011-11-29 2014-10-01 中国西电电气股份有限公司 1/2-period frequency measuring system and method
CN102497199A (en) * 2011-11-29 2012-06-13 中国西电电气股份有限公司 1/2-period frequency measuring system and method
CN102495283B (en) * 2011-12-09 2014-01-15 中国人民解放军第二炮兵计量站 Self-adaptive equal-precision frequency measuring method
CN102495283A (en) * 2011-12-09 2012-06-13 中国人民解放军第二炮兵计量站 Self-adaptive equal-precision frequency measuring method
CN102621384A (en) * 2012-04-09 2012-08-01 浙江中控技术股份有限公司 Frequency measuring method and frequency measuring system
CN102928677A (en) * 2012-11-09 2013-02-13 湖南航天远望测控技术有限公司 Nano pulse signal acquiring method
CN104931779A (en) * 2015-05-08 2015-09-23 中国电子科技集团公司第四十一研究所 Single-channel realized continuous frequency measure method
CN106302014A (en) * 2016-08-12 2017-01-04 电信科学技术第五研究所 The signal measurement method of wide-range high-precision
CN106302014B (en) * 2016-08-12 2019-08-27 电信科学技术第五研究所有限公司 The signal measurement method of wide-range high-precision
CN107247183A (en) * 2017-06-09 2017-10-13 中国电子科技集团公司第四十研究所 A kind of phase measuring system and method
CN107247183B (en) * 2017-06-09 2019-12-31 中国电子科技集团公司第四十一研究所 Phase measurement system and method
CN108647173A (en) * 2018-08-01 2018-10-12 中国电子科技集团公司第三十四研究所 A kind of synchronous start pulse signal regenerating unit and its operation method
CN108647173B (en) * 2018-08-01 2023-08-01 中国电子科技集团公司第三十四研究所 Synchronous trigger pulse signal regeneration device and operation method thereof
CN110954745A (en) * 2019-11-14 2020-04-03 中国航空工业集团公司西安航空计算技术研究所 High-precision frequency acquisition method and device based on FPGA
CN112698093A (en) * 2020-12-17 2021-04-23 南京爱浦克施电气有限公司 High-precision quick frequency measuring device

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Application publication date: 20110706